You know you're up too late writing when a story about a strange earl in medieval London strikes you. He is a mysterious characters, often seen skulking the streets at midnight. He becomes known as the Midnight Earl. The citizens eventually accuse him of witchcraft and burn him at the stake. You title your story "Burning the Midnight Earl."
This is what's called a red flag moment. Red flag! Red flag! Time to run away!
Sure, you want to dedicated and relentless about outworking your competition. Do it. But then you have to close the manuscript and pursue something else.
Hemingway said he made a point of exercising a lot in order to stay in top physical shape for those long stints of writing when inspiration really hit.
Inspiration is not hitting if your are burning the Midnight Earl. Understand? Keep your body healthy.
As an artist, you only get better with age. Don't neglect yourself yourself for your work. Stay well.